The present invention concerns a process for filleting meat material containing bones, especially from poultry, livestock, and pigs, as well as a device to carry out the process and where the filleted meat is kept mainly intact.
Previously known are machine-using methods for filleting of meat from bone-containing material. Such devices, however, suffer from several weaknesses both in construction and embodiments.
The general problem with filleting of bone containing meat material where the bone consists of a central bone which runs through the piece of meat, for instance a thigh-bone from chicken, lies in the shape of the bone. Generally, the bone consists of a more or less straight central bone secton with an expanded bone part, such as a knuckle on each end. These knuckles form an obstacle by mechanical pressing off of the meat from the bone, both as they are physically working as a stopper for the meat during the pressing off and in addition because knives which are used by the mechanical filleting have a tendency to dull when they cut into the bone material.
It is thus known within the art a machine from Protecon systems (Protecon Automatic Deboning Systems for Poultry, P.A.D.) for automatical filleting of thigh bones and wings from poultry. This system comprises i.a. a transport band with upwards extending pins for introduction of the meat pieces in the filleting machine. However, such an embodiment of the transport band will, when used, cause the meat material to stick between the pins and the transport band and prevent further operation of the machine before it has been cleaned. This will lead to a stop in the operation and wasted working time. A further drawback of such a machine is that possible broken bones in the material are not considered. In industrially handled material, there may be as much as up to 30-40% broken bones and this causes that the finished filleted material from the filleting machine may contain unacceptably large amounts of bone material.
Also the forms of the transport band represents a drawback by the mentioned type of machine. These forms have no possibility for regulation, so that small meat pieces will have a poor fastening and may thus be led the wrong way into the machine, while large meat pieces will lead to the previously mentioned clogging of the form pins on the transport band with the disadvantages this leads to.
Another known type of filleting machine is sold by Barker/FoodCraft and uses rotating knives for the removal of the meat from the bone of meat material. This machine does not consider bones broken before treatment of the piece of meat for filleting either, even if the distributor maintains that breaks caused by the use of the machine are reduced. One disadvantage of this type of machine is that the meat has a tendency to be ground into minced meat by the rotating knives, so that the production of whole fillets of meat is difficult to achieve.
A third type of filleting machine is known from European Patent Application No. PCT/AU84/00246 with international publication No. WO 85/02320. This type of filleting device however, utilizes a different principle from that of the present invention, since this known device uses water with high pressure to remove the meat from the bone of the treated meat pieces. Such an embodiment has, however, the disadvantages that the meat easily may become insipid and that the piece of bone must be fastened very firmly since the piece of meat rotates at high speed during the filleting process to remove the loosened meat by help of the centrifugal force, and will thus comprise a cumbersome process for this type of filleting.